Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting over 5.5 million people worldwide. Atrial fibrillation is the irregular, chaotic beating of the upper chambers of the heart. Electrical impulses discharge so rapidly that the atrial muscle quivers, or fibrillates. Episodes of atrial fibrillation may last a few minutes or several days. The most serious consequence of atrial fibrillation is ischemic stroke. It has been estimated that up to 20% of all strokes are related to atrial fibrillation. Most atrial fibrillation patients, regardless of the severity of their symptoms or frequency of episodes, require treatment to reduce the risk of stroke. The left atrial appendage (LAA) is a small organ attached to the left atrium of the heart as a pouch-like extension. In patients suffering from atrial fibrillation, the left atrial appendage may not properly contract with the left atrium, causing stagnant blood to pool within its interior, which can lead to the undesirable formation of thrombi within the left atrial appendage. Thrombi forming in the left atrial appendage may break loose from this area and enter the blood stream. Thrombi that migrate through the blood vessels may eventually plug a smaller vessel downstream and thereby contribute to stroke or heart attack. Clinical studies have shown that the majority of blood clots in patients with atrial fibrillation are found in the left atrial appendage. As a treatment, medical devices have been developed which are positioned in the left atrial appendage and deployed to close off the ostium of the left atrial appendage. Over time, the exposed surface(s) spanning the ostium of the left atrial appendage becomes covered with tissue (a process called endothelization), effectively removing the left atrial appendage from the circulatory system and reducing or eliminating the amount of thrombi which may enter the blood stream from the left atrial appendage.
A continuing need exists for improved medical devices and methods to control thrombus formation within the left atrial appendage of patients suffering from atrial fibrillation.